Thyrotropin-releasing hormone effects on phosphatidylinositol metabolism and binding in rat pituitary and retina

This paper reveals possible similarities in the thyrotropin-releasing hormone (TRH) effects on phospholipid metabolism in pituitary and retina of the rat central nervous system. Addition of the methylated analog (MeTRH) resulted in 171 +/- 16% and 88 +/- 10% increase in 32PO4 incorporation into phosphatidylinositol (PI) in pituitary (20 min incubation) and retina (60 min incubation), respectively. There was a similar significant increase in phosphatidic cid, but with no change in phosphatidylcholine or other classes of phospholipids. The effect was concentration-dependent and the ED50 also was close to KD, suggesting the response was regulated by MeTRH receptors in membranes of both pituitary and retina.